1. Field Of The Invention
The present invention generally relates to an apparatus for preparing stitch position-related data utilized by an embroidery sewing machine, and particularly to such an apparatus which automatically prepares stitch position-related data utilized by an embroidery sewing machine to embroider a predetermined area by forming stitches at respective stitch positions and filling the area with the formed stitches.
2. Related Art Statement
One of the Applicants has filed a U.S. patent application, the serial number of which has not been known to us, in which he proposes an apparatus for automatically preparing stitch position-related data utilized by an embroidery sewing machine. The proposed apparatus includes (a) dividing means for specifying a plurality of base positions on an outline of an area to be embroidered, based on outline data representative of the outline, the outline data including a plurality of sets of position data each of which is representative of a corresponding one of a plurality of specific positions predetermined on the outline, the base positions defining a polygon approximating the area, the dividing means defining a plurality of straight division lines each of which passes corresponding two of the base positions and which do not intersect each other inside the outline, the division lines dividing the area and the polygon into a plurality of sub-areas and a plurality of sub-polygons, respectively, each of the sub-areas being approximated by a corresponding one of the sub-polygons, and (b) data producing means for producing the stitch position-related data based on the sub-areas. The dividing means may divide a polygon as the area into a plurality of sub-polygons as the sub-areas, the specific positions consisting of vertices of the polygon, the base positions including the vertices. Areas, A, B and C, shown in FIGS. 36, 37 and 38, respectively, each are a polygon. In the case where the outline of an area is approximated by a function such as a spline function, the outline data may consist of sets of position data representative of points defined by the function.
An example of the dividing means includes means for determining the most distant, or approximately the most distant, two positions of the specific positions on the outline of the area, as a minimum and a maximum position of the area, and judging means for judging whether or not all straight segments obtained by connecting each of the distant two positions on the outline and each of the other specific positions on the outline are contained inside the outline, the dividing means dividing the area into divided areas as the sub-areas so that the judging means provides an affirmative judgment with respect to each of the divided areas. By this dividing means, the area A of FIG. 36 is divided into divided areas A.sub.1 -A.sub.7 as the sub-areas of the area, the area B of FIG. 37 into divided areas B.sub.1 and B.sub.2, and the area C of FIG. 38 into divided areas C.sub.1 -C.sub.4. The division of a predetermined area into divided areas by this dividing means, is effected for the purpose of reducing the direction of a straight line approximating each of the divided areas (hereinafter, referred to as the longitudinal direction of the divided area for the reason indicated later), to be generally parallel to the direction of a curved line or polygonal line approximating the same divided area which direction is taken at respective positions or portions on the curved or polygonal line (hereinafter referred to as the central-line direction of the divided area).
A second example of the dividing means includes means for determining the most distant, or approximately the most distant, two positions of the specific positions on the outline of said area, as a maximum and a minimum position of the area, means for determining a direction of a straight line passing the maximum and minimum positions as a longitudinal direction of the area, the outline consisting of a pair of portions which are opposed to each other with respect to the maximum and minimum positions, means for comparing a number of the specific positions on one of the opposed portions of the outline, with a number of the specific positions on the other portion thereof, and determines as a first portion of the outline one of the opposed portions which includes the smaller number of specific positions, and defining a plurality of straight first aid lines which are perpendicular to the longitudinal direction and each of which passes a corresponding one of the specific positions on the first portion of the outline and intersects the second portion of the outline, the first aid lines dividing the area and the outline into a plurality of first blocks and a plurality of first segments, respectively, each of the first blocks being enveloped by corresponding two of the first aid lines which are opposed to each other and corresponding two of the first segments which are opposed to each other, and means for modifying the each first block by selecting, as a division base position, one of the specific positions on the second portion of the outline which one position cooperates with the specific position associated with each of the opposed two first aid lines of the each first block to define, in place of the each first aid line, a corresponding one of the division lines which passes the associated specific position on the first portion of the outline and the division base position on the second portion of the outline, the base positions consisting of the specific positions, the sub-areas consisting of the each modified first block, the sub-areas including two triangle-like sub-areas to which the minimum and maximum positions belong, respectively. The first blocks except for the two triangle-like sub-areas or blocks are quadrangle-like sub-areas or blocks each approximated by a quadrangle. The modified first blocks are arranged in a row in the area. This dividing means may be operated on one or more of the divided areas produced by the above indicated first example of the dividing means. By this dividing means, the divided areas B.sub.1 and B.sub.2 of FIG. 37 are divided into blocks 1-4 (indicated at numbers enclosed by circles) and 5-8, respectively.
The central-line direction of a divided area produced from an area, or of an area, is more desirable as an embroidering direction in which direction to form stitches in the divided area, or blocks produced from the divided area or from the area, than the longitudinal direction thereof. By the way, the data producing means of the proposed apparatus provides stitch data for embroidering the divided area, or the blocks, by alternately and successively connecting with thread between stitch positions provided on one of the two portions of the divided area, or two segments of each of the blocks, which are opposed to each other in the direction perpendicular to the longitudinal direction of the divided block, or of the divided area, or the area, from which the blocks are produced, and stitch positions provided on the other portion, or other segment of the each block. However, the longitudinal direction of an area may sufficiently coincide with the central-line direction thereof, especially at opposite end portions thereof where the minimum and maximum positions thereof are located.
Generally, it is required that the sub-areas produced from an area have no triangle-like sub-area approximated by a triangle defined by three base positions specified on an outline of the area. However, when the polygon A of FIG. 36 is divided by the above indicated first type dividing means, the triangle divided area A.sub.3 is produced at an intermediate portion thereof. In addition, when a rectangle shown in FIG. 39 is divided by the second type dividing means, a pair of triangle blocks are produced at opposite end portions thereof where the minimum and maximum positions thereof are located. Furthermore, the polygon B of FIG. 37 includes two triangle blocks numbered four and five which are situated at two of four end portions of the divided areas B.sub.1, B.sub.2 as sub-areas but are not situated at end portions of the polygon B as an area.
In the case where a triangle-like sub-area is produced at an intermediate portion of an area, there arises a problem that a plurality of stitch positions are provided locally at a single base position on the sub-area as indicated at the divided area A.sub.3 in FIG. 40, and this problem leads to rendering the density of the stitches formed in the sub-area unequal to the density of the stitches formed in the other sub-areas. In addition, in the case where a triangle-like sub-area is produced at end portions of an area, there arises a problem that the embroidering direction of the stitches formed in the the sub-area may excessively be deflected, as indicated at arrows in the first and third blocks of FIG. 39, from the central-line direction of the area as taken at the sub-area which direction is more desirable as the embroidering direction for the sub-area.
In the above background, it is considered to provide modifying means for modifying the triangle-like sub-area to a quadrangle-like sub-area which is approximated by a quadrangle. For example, the modifying means modifies the first and third triangle-like blocks (triangles) of the rectangle D of FIG. 39, to a quadrangle that is the rectangle D itself, as shown in FIG. 41. When the data producing means provides stitch positions on the upper and lower sides of the rectangle D of FIG. 41 and the embroidery sewing machine embroiders the rectangle D by connecting with thread between the stitch positions, the embroidering direction of the stitches formed in the rectangle D coincides with the central-line direction thereof.
A first example of the modifying means modifies a triangle-like sub-area actually produced by the dividing means, to a quadrangle-like sub-area. In this case, the modifying means may judge, each time an area is divided into two sub-areas, whether or not each of the two sub-areas is a triangle-like sub-area, and if an affirmative judgment is provided, modify the triangle-like sub-area to a quadrangle-like sub-area. Alternatively, the modifying means may judge, after an area is completely divided into a plurality of sub-areas, whether or not each of the sub-areas is a triangle-like sub-area, and if an affirmative judgment is provided, modify the triangle-like sub-area to a quadrangle-like sub-area.
In the case where an area is divided into blocks by the above indicated second type dividing means, two triangle-like sub-areas inevitably are produced at the two particular portions to which the minimum and maximum positions thereof belong, respectively, irrespective of the shape or profile of the area. A second example of the modifying means is operated on the particular portions of the area for modifying each of the two triangle-like sub-areas to a quadrangle-like sub-area. Furthermore, it is possible to operate the dividing means to divide the area so that the particular portions be divided into quadrangle-like sub-areas. In this case, no triangle-like sub-area is produced as an actual sub-area.
As is apparent from the foregoing, it is possible to divide an area into sub-areas such that the sub-areas include no triangle-like sub-area. However, there are cases where it is not appropriate to provide no triangle-like sub-area, namely, where if stitches are formed in an area including no triangle-like sub-area, the embroidering direction of the stitches formed does not sufficiently coincide with the central-line direction of the area. FIG. 42 shows an area as an example of such cases. The area of FIG. 42 includes a triangle-like sub-area which is symmetrical with respect to the central-line direction of the area and simultaneously protrudes outward. Hereinafter, areas analogous to the area of FIG. 42 are referred to as the rhombus-type areas. If a rhombus-type area is divided into sub-areas such that no triangle-like sub-area is provided at a particular portion thereof, then there arises a problem that, at the particular portion of the area, stitches are formed in an inappropriate direction that does not sufficiently coincide with the central-line direction of the area, as indicated at arrows in FIG. 42.